package com.dy.分类.链表.两数相加;

import com.dy.分类.链表.ListNode;

/*
两数相加
给出两个 非空 的链表用来表示两个非负的整数。其中，它们各自的位数是按照 逆序 的方式存储的，并且它们的每个节点只能存储 一位 数字。

如果，我们将这两个数相加起来，则会返回一个新的链表来表示它们的和。

您可以假设除了数字 0 之外，这两个数都不会以 0 开头。

示例：

输入：(2 -> 4 -> 3) + (5 -> 6 -> 4)
输出：7 -> 0 -> 8
原因：342 + 465 = 807
 */
public class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        int flag = 0;
        ListNode res = new ListNode((l1.val + l2.val) % 10);
        ListNode tail = res;
        flag = (l1.val + l2.val) / 10;
        l1 = l1.next;
        l2 = l2.next;
        while (l1 != null && l2 != null) {
            int tmp = l1.val + l2.val + flag;
            int supplement = tmp % 10;
            flag = tmp / 10;
            ListNode t = new ListNode(supplement);
            tail.next = t;
            tail = t;
            l1 = l1.next;
            l2 = l2.next;
        }
        if (l1 != null) {

            tail.next = l1;
            tail = tail.next;
            while (tail.next != null) {
                int tmp = tail.val + flag;
                flag = tmp / 10;
                tail.val = tmp % 10;
                if (flag == 0) break;
                tail = tail.next;
            }
            int tmp = tail.val + flag;
            flag = tmp / 10;
            tail.val = tmp % 10;


        } else if (l2 != null) {
            tail.next = l2;
            tail = tail.next;
            while (tail.next != null) {
                int tmp = tail.val + flag;
                flag = tmp / 10;
                tail.val = tmp % 10;
                if (flag == 0) break;
                tail = tail.next;
            }
            int tmp = tail.val + flag;
            flag = tmp / 10;
            tail.val = tmp % 10;
        }

        if (flag == 1) {
            ListNode t = new ListNode(1);
            tail.next = t;
        }

        return res;

    }
    //简便
    public ListNode addTwoNumbers2(ListNode l1, ListNode l2) {
        ListNode dummyHead = new ListNode(0);
        ListNode p = l1, q = l2, curr = dummyHead;
        int carry = 0;
        while (p != null || q != null) {
            int x = (p != null) ? p.val : 0;
            int y = (q != null) ? q.val : 0;
            int sum = carry + x + y;
            carry = sum / 10;
            curr.next = new ListNode(sum % 10);
            curr = curr.next;
            if (p != null) p = p.next;
            if (q != null) q = q.next;
        }
        if (carry > 0) {
            curr.next = new ListNode(carry);
        }
        return dummyHead.next;
    }
}
